| 摘要 |
<p>A ram assembly (10) having a casing (14) defining a piston chamber; a piston rod (20) slidable into and out of the casing between a retracted state and an extended state, a free end (22) of the piston rod being located in said piston chamber. A piston head (30) is located in the casing and is slidable therein separately from the piston rod. The piston head (30) is located between the inlet (42) and the outlet (44), and between said chamber and the inlet (42) and has a bore (36) to allow hydraulic liquid to pass threrethrough. The ram assembly (10) is operable between a first mode of use in which the bore (36) is open and the piston head (30) is positioned to isolate the piston chamber from the outlet (44) and to allow operating fluid flowing through the bore (36) to enter the chamber, and a second mode of use in which the bore (36) is closed and the piston head (30) is positioned so that the chamber is in fluid communication with said outlet (44).</p> |
